Question

An urn contains nine balls of which three are red, four are blue and two are green. Three balls are drawn at random without replacement from the urn. The probability that the three balls have different colour is

Answer 1

Here we have to consider 3 cases.

Case 1- all balls are different colour

Case 2- 2 balls are same coloured

Case 3- all balls are same coloured

So let the events be E1, E2 and E3 respectively.

P(E1) =P(E2) =P(E3) =1/3

Let A be the event of drawing balls from the urn

Then simply solve it by bayes' theorem